Incorporation of a volume translation in an equation of state for fluid mixtures: which combining rule? which effect on properties of mixing?

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• 作者：Romain Privat ; ^{romain.privat@univ-lorraine.fr" class="auth_mail" title="E-mail the corresponding author} ; Jean-Noë ; l Jaubert ; Yohann Le Guennec
• 关键词：Volume translation ; Volume correction ; Equation of state ; Property of mixing ; Equilibrium conditions
• 刊名：Fluid Phase Equilibria
• 出版年：2016
• 出版时间：15 November 2016
• 年：2016
• 卷：427
• 期：Complete
• 页码：414-420
• 全文大小：240 K

文摘

In a previous work, we showed that the incorporation of a temperature-dependent volume-translation parameter in an equation of state for pure components alters necessarily the prediction of 1-phase and 2-phase properties. On the contrary, if a temperature-independent volume translation parameter is used, most of the 1-phase and 2-phase properties are preserved.

In the present study, the influence of the incorporation of a volume translation in an equation of state, on mixture properties (essentially phase equilibria and properties of mixing) is addressed. It is first assumed that the volume-translation parameter of a mixture (c) is related to mole fractions through a quadratic mixing rule involving mutual volume translation parameters (c_ij). It is found that only a simple arithmetic-mean combining rule for c_ij makes it possible to preserve phase equilibria. Using such a combining rule entails that the quadratic mixing rule for the c parameter degenerates to a linear mixing rule.

Secondly, it is proved that properties of mixing (g^M, h^M, s^M, c_P^M …) are preserved if a linear mixing rule is used for the c parameter and altered otherwise.